Investigations toward multistatic passive radar imaging

Potential for imaging in passive multistatic radar systems is investigated primarily in terms of illuminator type and coherency. A typical set of transmitters in the UHF and VHF bands based upon the local illuminators in the Columbus, Ohio region is presented to constitute a realistic passive imaging environment. A passive radar signal model is then developed and demonstrates one possible processing implementation for imaging across multiple distributed illuminators. From this, the spatial frequency representation of an airborne target traversing a common flight path is presented. This k-space formulation is assessed as a tool for predicting imaging performance, along with potential limitations of the approach for accurately modeling realistic imaging scenarios of multistatic passive radar systems. Finally, simulation results show the -3 dB point target response to be <;1 m for FM transmitters and <;0.2 m for DTV, for the realistic Columbus-based imaging environment.

I. Introduction

Passive radar systems, which utilize transmitters of opportunity, have been shown to successfully detect and track aircraft [1]–[2]. The systems rely on broadcast transmissions, primarily in the UHF and VHF bands, as their source of RF illumination, relieving the radar of the need for high powered transmit hardware. This system design benefits from lower costs compared to traditional radars and the multitude of high powered transmissions available. Reduced spectral congestion and covert operation are also advantages, but passive radar presents other unique challenges that must be dealt with. First, the transmit waveforms are unknown and often not well suited for radar purposes. Second, the bistatic geometries associated with passive radar also complicate the processing and add a spatial dependence on the Doppler sensitivity and range resolution.